Heat Pump System Operation & Components
A heat pump system is made up of four major components:
- The outdoor unit or heat pump is the unit that sits outside your home and contains the compressor, condensing coil, reversing valve, defrost control, fan and motor and all the systems electrical components.
- The air handler is the name given to the combined evaporator coil, blower motor and electric heater pack. The air handler must be properly matched to the outside unit and should always be replaced when you purchase a new system in order to maintain maximum system efficiency and prolong the life of your new heat pump. If you don’t replace the air handler the outdoor unit will fail prematurely.
- The heater pack is the electric heat elements that are installed in the air handler. When the heat pump cannot keep up with the homes demand for heat the electric elements cycle on. The heater pack is also known as emergency heat in the sense that it can be used when your heat pump has failed.
- The line set The line set is the copper tubing that connects the air handler to the heat pump. The black insulation or armaflex on this tubing keeps it from sweating as the cold refrigerant passes through it. The line set should be replaced whenever possible to avoid contamination and to help extend the life of the new equipment.
- Variable Speed Blower Motor In addition to the 4 major components, you also have the option of adding a Variable speed Blower motor to your Heat Pump System. When you purchase a heat pump you are purchasing a system. The pump outside is matched with the air handler inside. The blower on the air handler is critical to the operation of the pump. That’s where variable speed comes in. The variable speed blower increases the efficiency of the system because the GE ECM motor is electrically more efficient than standard motors. When you run your fan continuously this motor costs up to 90% less to operate than a standard blower motor. Variable speed also increases comfort. It ramp starts, slowly bring the fan up to speed helping to avoid the sudden burst of air most systems deliver. Variable speed runs at a slower speed in continuous operation, using about as much energy as a 100-watt light bulb, as it constantly circulates the air in your home. This evens out hot or cold spots, without feeling a draft. This reduces air velocity making your air cleaner and humidifier more efficient. This motor even compensates for a dirty air filter by running faster as it senses air filter restriction. Again, because you are purchasing a system, the variable speed option can be added to any one of the three heat pump choices in your proposal.
Here's how a Heat Pump Works
In the summer a heat pump uses refrigerant, pumped by the compressor, to transport the hot air inside your home outside. The heat pump coil outside dumps the heat into the atmosphere while the coil inside the air handler releases cool air into your home while at the same time absorbing heat and repeating the cycle again. The air handler fan distributes the cool air inside your home while the heat pump fan dumps the hot air outside. In the winter reverse the cycle. There is always some heat in the air outside. The heat pump captures that heat, pumps it inside and releases it in your home. Unfortunately there is also moisture in the outside air. This causes frost build up on your heat pump and it must remove this frost to stay efficient. To do this the pump quickly turns back into an air conditioner causing the ice to melt on the outside coil. As soon as the ice is melted it reverses back into a heat pump. Now you know what a defrost control and reversing valve do! As it gets colder out the heat in the atmosphere is harder to find and your electric heaters will cycle to supplement the pump. Why not just use the electric heat? Because pumping heat from outside can be up to 300% more efficient than using electric heaters. In other words, you use the heat pump because it saves you money. Of course a heat pump is not quite that simple but for our purposes lets leave it at that.